TEXT: H value  of  the  saturation current temperature exponent,TEXT: H XTI, is usually 2.TEXT: HTEXT: HTEXT: HTEXT: H      Temperature appears explicitly in the value of junctionTEXT: H potential, U (in spice PHI), for all the device models.  TheTEXT: H temperature dependence is determined by:TEXT: HTEXT: HTEXT: H                                   | N N   |TEXT: H                                      a dTEXT: H                          kT       |------ |TEXT: H                   U(T) = --  log        2TEXT: H                           q     e |N (T)  |TEXT: H                                     iTEXT: HTEXT: HTEXT: H where k is Boltzmann's constant,  q  is  the  electronicTEXT: H charge,  N   is the acceptor impurity density, N  is theTEXT: H           a                                     dTEXT: H donor impurity density, N  is the intrinsic carrier con-TEXT: H                          iTEXT: H centration, and E  is the energy gap.TEXT: H                  gTEXT: HTEXT: HTEXT: HTEXT: H      Temperature appears explicitly in the value of  surfaceTEXT: H mobility, M  (or UO), for the MOSFET model.  The temperatureTEXT: H            0TEXT: H dependence is determined by:TEXT: HTEXT: HTEXT: H                                M (T )TEXT: H                                 0  0TEXT: H                       M (T) = -------TEXT: H                        0          1.5TEXT: H                               | T|TEXT: H                               |--|TEXT: H                               |T |TEXT: H                                 0TEXT: HTEXT: HTEXT: HTEXT: HTEXT: HTEXT: HTEXT: H      The effects of temperature on resistors is  modeled  byTEXT: H the formula:TEXT: HTEXT: HTEXT: H                                                    2TEXT: H       R(T) = R(T ) [1 + TC  (T - T ) + TC  (T - T ) ]TEXT: H                 0         1       0      2       0TEXT: HTEXT: HTEXT: HTEXT: H where T is the circuit temperature, T   is  the  nominalTEXT: H                                      0TEXT: H temperature,  and TC  and TC  are the first- and second-TEXT: H                     1       2TEXT: H order temperature coefficients.TEXT: HSUBJECT: CONVERGENCETITLE: CONVERGENCETEXT: HTEXT: H _1._3.  _C_O_N_V_E_R_G_E_N_C_ETEXT: HTEXT: HTEXT: H      Both dc and transient  solutions  are  obtained  by  anTEXT: H iterative  process which is terminated when both of the fol-TEXT: H lowing conditions hold:TEXT: HTEXT: HTEXT: H 1)   The nonlinear branch  currents  converge  to  within  aTEXT: H      tolerance of 0.1% or 1 picoamp (1.0e-12 Amp), whicheverTEXT: H      is larger.TEXT: HTEXT: H 2)   The node voltages converge to  within  a  tolerance  ofTEXT: H      0.1% or 1 microvolt (1.0e-6 Volt), whichever is larger.TEXT: HTEXT: H      Although the algorithm used in SPICE has been found  toTEXT: H be  very  reliable,  in some cases it fails to converge to aTEXT: H solution.  When this failure occurs, the program  terminatesTEXT: H the job.TEXT: HTEXT: H      Failure to converge in dc analysis is usually due to anTEXT: H error  in specifying circuit connections, element values, orTEXT: H model parameter values.  Regenerative switching circuits  orTEXT: H circuits  with  positive feedback probably will not convergeTEXT: H in the dc analysis unless the OFF option is used for some ofTEXT: H the  devices  in  the feedback path, or the .NODESET controlTEXT: H line is used to force the circuit to converge to the desiredTEXT: H state.SUBJECT: CIRCUIT DESCRIPTIONTITLE: CIRCUIT DESCRIPTIONTEXT: HTEXT: H _2.  _C_I_R_C_U_I_T _D_E_S_C_R_I_P_T_I_O_NSUBTOPIC: SPICE:GENERAL STRUCTURE AND CONVENTIONSSUBTOPIC: SPICE:TITLE LINE COMMENT LINES AND .END LINESUBTOPIC: SPICE:DEVICE MODELSSUBTOPIC: SPICE:SUBCIRCUITSSUBTOPIC: SPICE:COMBINING FILESSUBJECT: GENERAL STRUCTURE AND CONVENTIONSTITLE: GENERAL STRUCTURE AND CONVENTIONSTEXT: HTEXT: H _2._1.  _G_E_N_E_R_A_L _S_T_R_U_C_T_U_R_E _A_N_D _C_O_N_V_E_N_T_I_O_N_STEXT: HTEXT: HTEXT: H      The circuit to be analyzed is described to SPICE  by  aTEXT: H set  of element lines, which define the circuit topology andTEXT: H element values, and a set of control lines, which define theTEXT: H model  parameters  and  the run controls.  The first line inTEXT: H the input file must be the title, and the last line must  beTEXT: H ".END".   The  order  of  the  remaining  lines is arbitraryTEXT: H (except, of course, that continuation lines must immediatelyTEXT: H follow the line being continued).TEXT: HTEXT: H      Each element in the circuit is specified by an  elementTEXT: H line  that  contains  the element name, the circuit nodes toTEXT: H which the element is connected, and the values of the param-TEXT: H eters  that  determine the electrical characteristics of theTEXT: H element.  The first letter of the element name specifies theTEXT: H element  type.   The  format  for the SPICE element types isTEXT: H given in what follows.  The strings  XXXXXXX,  YYYYYYY,  andTEXT: H ZZZZZZZ denote arbitrary alphanumeric strings.  For example,TEXT: H a resistor name must begin with the letter R and can containTEXT: H one  or  more  characters.   Hence,  R,  R1,  RSE, ROUT, andTEXT: H R3AC2ZY are valid resistor names.  Details of each  type  ofTEXT: H device are supplied in a following section.TEXT: HTEXT: H      Fields on a line are separated by one or more blanks, aTEXT: H comma,  an equal ('=') sign, or a left or right parenthesis;TEXT: H extra spaces are ignored.  A line may be continued by enter-TEXT: H ing  a  '+'  (plus) in column 1 of the following line; SPICETEXT: H continues reading beginning with column 2.TEXT: HTEXT: H      A name field must begin with a letter (A through Z) andTEXT: H cannot contain any delimiters.TEXT: HTEXT: HTEXT: H      A number field may be an integer  field  (12,  -44),  aTEXT: H floating  point field (3.14159), either an integer or float-TEXT: H ing point number followed by  an  integer  exponent  (1e-14,TEXT: H 2.65e3),  or  either  an  integer or a floating point numberTEXT: H followed by one of the following scale factors:TEXT: HTEXT: H       12         9                    6         3               -6TEXT: H T = 10     G = 10             Meg = 10    K = 10      mil = 25.4TEXT: H       -3                 -6         -9          -12         -15TEXT: H m = 10     u (or  M) = 10     n = 10      p = 10      f = 10TEXT: HTEXT: HTEXT: HTEXT: H Letters immediately following a number that  are  not  scaleTEXT: H factors  are  ignored,  and  letters immediately following aTEXT: H scale factor are ignored.  Hence, 10, 10V, 10Volts, and 10HzTEXT: H all  represent  the  same number, and M, MA, MSec, and MMhosTEXT: H all represent  the  same  scale  factor.   Note  that  1000,TEXT: H 1000.0,  1000Hz,  1e3, 1.0e3, 1KHz, and 1K all represent theTEXT: H same number.TEXT: HTEXT: H      Nodes names may be arbitrary  character  strings.   TheTEXT: H datum  (ground) node must be named '0'.  Note the differenceTEXT: H in SPICE3 where the nodes are treated as  character  stringsTEXT: H and not evaluated as numbers, thus '0' and '00' are distinctTEXT: H nodes in SPICE3 but not in SPICE2.  The circuit cannot  con-TEXT: H tain  a  loop of voltage sources and/or inductors and cannotTEXT: H contain a cut-set  of  current  sources  and/or  capacitors.TEXT: H Each  node  in  the  circuit  must have a dc path to ground.TEXT: H Every node must have at least  two  connections  except  forTEXT: H transmission line nodes (to permit unterminated transmissionTEXT: H lines) and MOSFET substrate nodes (which have  two  internalTEXT: H connections anyway).TEXT: HSUBJECT: TITLE LINE COMMENT LINES AND .END LINETITLE: TITLE LINE, COMMENT LINES AND .END LINETEXT: HTEXT: H _2._2.  _T_I_T_L_E _L_I_N_E, _C_O_M_M_E_N_T _L_I_N_E_S _A_N_D ._E_N_D _L_I_N_ETEXT: HSUBTOPIC: SPICE:Title LineSUBTOPIC: SPICE:.END LineSUBTOPIC: SPICE:CommentsSUBJECT: Title LineTITLE: Title LineTEXT: HTEXT: H _2._2._1.  _T_i_t_l_e _L_i_n_eTEXT: HTEXT: HTEXT: H _E_x_a_m_p_l_e_s:TEXT: HTEXT: H     POWER AMPLIFIER CIRCUITTEXT: H     TEST OF CAM CELLTEXT: HTEXT: HTEXT: H      The title line must be the first  in  the  input  file.TEXT: H Its  contents  are  printed verbatim as the heading for eachTEXT: H section of output.TEXT: HTEXT: HSUBJECT: .END LineTITLE: .END LineTEXT: HTEXT: H _2._2._2.  ._E_N_D _L_i_n_eTEXT: HTEXT: HTEXT: H _E_x_a_m_p_l_e_s:TEXT: HTEXT: H     .ENDTEXT: HTEXT: HTEXT: H      The "End" line must always be the last in the inputTEXT: H file.   Note  that the period is an integral part of theTEXT: H name.TEXT: HTEXT: HTEXT: HSUBJECT: CommentsTITLE: CommentsTEXT: HTEXT: H _2._2._3.  _C_o_m_m_e_n_t_sTEXT: HTEXT: H _G_e_n_e_r_a_l _F_o_r_m:TEXT: HTEXT: H     * <any comment>TEXT: HTEXT: HTEXT: H _E_x_a_m_p_l_e_s:TEXT: HTEXT: H     * RF=1K      Gain should be 100TEXT: H     * Check open-loop gain and phase marginTEXT: HTEXT: HTEXT: H      The asterisk in the  first  column  indicates  thatTEXT: H this  line  is  a  comment  line.   Comment lines may beTEXT: H placed anywhere in the circuit description.   Note  thatTEXT: H SPICE3  also considers any line with leading white spaceTEXT: H to be a comment.TEXT: HTEXT: HSUBJECT: DEVICE MODELSTITLE: DEVICE MODELSTEXT: HTEXT: H _2._3.  _D_E_V_I_C_E _M_O_D_E_L_STEXT: HTEXT: H _G_e_n_e_r_a_l _f_o_r_m:TEXT: HTEXT: H     .MODEL MNAME TYPE(PNAME1=PVAL1 PNAME2=PVAL2 ... )TEXT: HTEXT: HTEXT: H _E_x_a_m_p_l_e_s:TEXT: HTEXT: H     .MODEL MOD1 NPN (BF=50 IS=1E-13 VBF=50)TEXT: HTEXT: HTEXT: HTEXT: H      Most simple circuit elements typically require  only  aTEXT: H few  parameter values.  However, some devices (semiconductorTEXT: H devices in particular) that are included  in  SPICE  requireTEXT: H many parameter values.  Often, many devices in a circuit areTEXT: H defined by the same set of  device  model  parameters.   ForTEXT: H these  reasons,  a set of device model parameters is definedTEXT: H on a separate .MODEL line and assigned a unique model  name.TEXT: H The  device  element  lines in SPICE then refer to the modelTEXT: H name.TEXT: HTEXT: H      For these more complex device types, each  device  ele-TEXT: H ment  line  contains the device name, the nodes to which theTEXT: H device is connected, and the device model  name.   In  addi-TEXT: H tion,  other  optional  parameters may be specified for someTEXT: H devices:  geometric factors and an  initial  condition  (seeTEXT: H the following section on Transistors and Diodes for more de-TEXT: H tails).TEXT: HTEXT: H      MNAME in the above is the model name, and type  is  oneTEXT: H of the following fifteen types:TEXT: HTEXT: H             R      Semiconductor resistor modelTEXT: H             C      Semiconductor capacitor modelTEXT: H             SW     Voltage controlled switchTEXT: H             CSW    Current controlled switchTEXT: H             URC    Uniform distributed RC modelTEXT: H             LTRA   Lossy transmission line modelTEXT: H             D      Diode modelTEXT: H             NPN    NPN BJT modelTEXT: H             PNP    PNP BJT modelTEXT: H             NJF    N-channel JFET modelTEXT: H             PJF    P-channel JFET modelTEXT: H             NMOS   N-channel MOSFET modelTEXT: H             PMOS   P-channel MOSFET modelTEXT: H             NMF    N-channel MESFET modelTEXT: H             PMF    P-channel MESFET modelTEXT: HTEXT: HTEXT: HTEXT: H      Parameter values are defined by appending the parameterTEXT: H name  followed  by  an  equal  sign and the parameter value.TEXT: H Model parameters that are not given a value are assigned theTEXT: H default  values  given  below  for each model type.  Models,TEXT: H model parameters, and default values are listed in the  nextTEXT: H section along with the description of device element lines.TEXT: HSUBJECT: SUBCIRCUITSTITLE: SUBCIRCUITSTEXT: HTEXT: H _2._4.  _S_U_B_C_I_R_C_U_I_T_STEXT: HTEXT: HTEXT: H      A subcircuit that consists of  SPICE  elements  can  beTEXT: H defined  and  referenced  in  a  fashion  similar  to deviceTEXT: H models.  The subcircuit is defined in the input  file  by  aTEXT: H grouping  of  element lines;  the program then automaticallyTEXT: H inserts the group of elements  wherever  the  subcircuit  isTEXT: H referenced.   There is no limit on the size or complexity ofTEXT: H subcircuits, and subcircuits may contain other  subcircuits.TEXT: H An example of subcircuit usage is given in Appendix A.TEXT: HTEXT: HSUBTOPIC: SPICE:.SUBCKT LineSUBTOPIC: SPICE:.ENDS LineSUBTOPIC: SPICE:Subcircuit Calls